Refrigeration circuit for heat pumps



April 17, 1962 G. c:` sMlTH ETAL 3,029,614,

REFRIGERATION CIRCUIT FOR HEAT PUMPS Filed April l2, 1961 C D 22 www. 24 c o CD D HEAT HEAT/'Q Q D EXCHANCER EXCHANGER D D D CIL/m I4 le laf@ D C: D D Q D D D D 5--6 INVENTOM 4o GERALD c. SMITH P TER WIATR K ELVIN KLATEF e4 34 e072 B278 f ice 3,029,614 RnrnrennATroN Cmcnrr ron HEAT PUMPS and Melvin H. Klatt, Tex., assignors to Ed Friedrich, Antonio, Tex., a corporation of Filed Apr. 12, 1961, Ser. No. 102,589 Claims. (Cl. 62-324) This invention relates to refrigeration circuits for heat pumps of the type incorporating a reversible mechanical refrigeration system having an inside heat exchanger and an outside heat exchanger. More particularly, it concerns such refrigeration circuits in which a plurality of restrictors are employed selectively to achieve optimum efficiency of operation regardless of whether the heat pump is heating or cooling.

In heat pumps of the type aforementioned, and particularly such heat pumps in the form of window units, it has been found desirable to utilize capillary tubing between the heat exchangers as a restriction through which the refrigerant is pumped to provide the required expansion thereof into the heat exchanger being used as the evaporator. One of the basic problems involved in the use of such capillary tubing is due to the fact that a capillary tube of a given bore and and length is efficient only over a very narrow range of refrigeration loads. This problem is especially acute in reversible type refrigeration systems used as heat pumpsbecause of the extremely diverse conditions encountered during use of the system to supply heat. For this reason, in heat pumps of this type heretofore available, it has been the practice to arrange a plurality of capillary tubing lengths in series, one or more of the lengths being provided with a bypass so that the length of capillary tubing in the refrigerant circuit between the heat exchangers may be variedA to achieve higher eiiiciency under differing load requirements. See, for example, U.S. Patent No. 2,720,75 6. In such prior art devices, however, diiculties are encountered in providing adequate means for filtering and otherwise conditioning the refrigerant. Desirably, such a lter means should be positioned between the heat exchangers in the refrigeration system and preferably in advance of the capillary tubing, since dirt and other foreign particles are most likely to become entrained in the refrigerant as it passes through the heat exchangers, and, of course, should be removed therefrom as quickly as possible to bring about proper -functioning of the components in the system. In systems of the type wherein a plurality of capillary tubing lengths are arranged in series, the refrigerant must pass through at least one length of the tubing in both directions upon reversal of the system and accordingly there is no provision by which the refrigerant may be filtered or otherwise conditioned immediately prior to entering the capillary tubing. In other words, the location of a filter or other conditioning means in such a system between the heat exchangers would be effective to trap dirt and other foreign particles upon refrigerant flow in one direction, but upon reversal of the system, particles which had been trapped previously would be washed into the refrigerant, thereby defeating its purpose.

Accordingly, a principal `object of this invention is to provide a refrigerant circuit for =a heat pump of the type incorporating a reversible mechanical refrigeration system by which the above-mentioned problems are effectively and substantially overcome.

Another object of this invention is to provide a heat pump in the form of a reversible mechanical refrigeration system having inside and outside heat exchangers, vwith an effective arrangement of capillary tubes between the heat exchangers by which optimum efficiency is realized both during heating and cooling cycles of oper-ation.

A further object of this invention is the provision of a refrigerant circuit between the heat exchangers of a heat pump of the type referred to including variable lengths of capillary tubing and a refrigerant conditioning means arranged to be effective both during heating and cooling cycles of operation without danger of backwash and the resulting introduction of foreign particles into the refrigerant upon reversal of the system.

Other objects and further scope of applicability of the present invention will 'become apparent upon the detailed description given hereinafter. It should be understood, however, that the detailed description, while indicating preferred embodiments of the invention is given by way of illustration only, since i-t will4 become apparent to those skilled in the art from this description that various changes and modifications can be made without departing from the true spirit and scope of this invention.

In general, the aforementioned objects are accomplished by providing a refrigerant circuit between the inside and outside heat exchangers of a reversible mechanical refrigeration system type heat pump with at least two flow restrictors, preferably in the form of lengths of capillary tubing having different flow characteristics so that one produces optimum efficiency duringra cooling cycle operation While the other provides optimum efficiency during heating. In parallel with each of the restrictors or lengths of tubing are bypass conduits terminating at and opening into respective inlets of a valve means which has Aan outlet opening into a refrigerant conditioning means such as a ilter dryer unit or the like that opens, in turn, into the restrictors at a point intermediate thereof. The valve means preferably is a two-way check Valve arranged such that one inlet thereof is open to permit flow from one of the heat exchangers to the other through the refrigerant conditioning means and one of the flow restrictors upon operation of the system in one direction and refrigerant flow into the other inlet thereof through the refrigerant conditioning means and the other restrictor upon reversal of the system.

A more complete understanding of the invention and its method of operation may be had by reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of the heat pump of this invention during the cooling cycle of operation;

FIG. 2 is -a schematic drawing of the heat pump of this invention during the heating cycle thereof; and

FIGS. 3 and 4 are schematic drawings illustrating alternate forms of valve means usable in the circuit of this invention.

Referring now in detail to the drawings, the heat pump with which the present invention is adapted, to be used, is a closed circuit, reversible mechanical refrigeration system, including an inside heat exchanger 10, an outside heat exchanger 12, a compressor 14 and a reversing valve 16. The compressor is supplied with low pressure refrigerant through a conduit 18 and delivers high pressure refrigerant through a conduit 20 to the reversing valve 16. A conduit 22 extends between the inside heat exchanger 10 and the reversing valve, While a conduit 24 extends between the reversing valve and theoutside heat exchanger l2. As will be understood by those familiar in the art, all of the components of the system are mounted in a casing or housing as a unit such as those capable of being mounted in a window with the inside heat exchanger exposed within the enclosurerto be treated and the outside heat exchanger exposed to outside air. Also, in the operation of the heat pump, when the reversing valve is positioned as shown in FIG. 1, the recondensation.

frigerant is compressed in the compressor, pumped to the outside heat exchanger wherein the refrigerant is condensed to liquid and deprived of heat, passed through a restriction and expanded into the inside coil or evaporator to cool enclosure in which lthe inside heat exchanger is located and returned to the compressor. During the heating cycle, this procedure is vreversed as shown in FIG. 2 so that the compressed refrigerant is delivered to the inside heat exchanger wherein it condenses and gives off heat, passed through a restriction and expanded into the outside heat exchanger wherein it takes on heat, by evaporation and returned to the compressor. The system thus far described is conventional, and as such,

`by itself forms no part of the present invention.

The refrigerant circuit between the heat exchangers on the opposite side thereof from the compressor includes a rst restrictor, preferably in the form of a length or coil of capillary tubing 26 and a second restrictor or length of capillary tubing in the form of coil 28. Conduit means 30 and 32 extend between the coil 26 and the inside heat exchanger and the coil 28 and the outside heat exchanger respectively. A first bypass conduit 34 is in parallel with the coil 26 opening at one end in the conduit 30 and at the other end into an inlet 36 in a twoway check valve 38.y Similarly, a second conduit 4d extends in parallel with thecoil 28 and is open to the conduit 32 at one end while its other end opens to another inlet 42 in the valve 38. As indicated, the valve 38 is preferably in the form of a two-Way check Valve vhaving a ball 44, which seats in the inlet 36 under the influence of refrigerant flow through the inlet 42 and correspondingly, the ball 44 seats in the inlet 42 upon refrigerant ow into the valve through the inlet 36 thereof.

The valve 38 is provided with an outlet port 46, which opens into a refrigerant conditioning means such as a filter-dryer unit 4S. The unit 41S is of conventional design, functioning to lter and dry the refrigerant asit passes therethrough, and a further explanation thereof is deemed unnecessary herein, except to note that the filter-dryer unit outlets at 49 into the conduit 50 at a point midway between the capillary `tubing Vcoils 26 and 28.

In operation, the direction of refrigerant flow during cooling is in the direction of the arrows illustrated in FIG. 1. Thus, it will `be noted Ythat after the refrigerant passes the outside heat exchanger 12, it enters the conduit 32 and because of the restriction to flow olfered by the coil 28, passes into the conduit 40. From there, the refrigerant enters the valve 38 and because the ball 44 thereof is moved to a position of seating against the inlet port 36, the refrigerant passes through the valve outlet 46, the filter-dryer unit 48, the conduit V50 and the capillary tubing coil 26. The refrigerant does not enter the coil 28 because of the relatively high Vstatic pressure therein as compared with that of the "coil 26 and because it is isolated by high pressure liquid. Upon leaving the coil 26, the refrigerant is expanded and enters the inside heat exchanger 10, wherein it takes on latent heat of evaporation to cool the enclosure in which the heat exchanger 10` is mounted.

To heat the enclosure in which the heat exchanger 10 is mounted, the reversing valve 16 is adjusted to reverse the direction of refrigerant flow so that high pressure refrigerant is delivered to the inside heat exchanger wherein it condenses, thereby giving off latent heatof From the inside heat exchanger 10, the high pressure refrigerant passes into the conduit 30', and-'because of the restriction offered by the coil 26, passes into the bypass conduit 34 to the'valve 38. It will be noted that the ball 44 of the valve has now moved to seat against the inlet 42, thereby causing the refrigerant to again pass through the outlet 46, the filter-dryer unit 48, and into'the conduit 5U. Because the coil 26 is isolated by the influence of high pressure, the refrigerant flows through the coil .28 from which it is expanded into the outside heat exchanger 12, wherein it takes on latent heat of evaporation and returned to the compressor as aforementioned.

Modified forms of valve means adapted to be used with the refrigeration circuit of this invention are shown in FIGS. 3 and 4. In the embodiment of FIG. 3, the valve means, like the valve described above, includes a housing 52 to which the conduits 34 and 40 are connected at inlets S4 and 56 respectively. Each of the inlets open to vertical ball chambers 5S and 60 in which gravity biased ball checks 62 and 64 are movably situated. The cha-mbers, in turn open to a valve outlet 66. Operation of this valve in the circuit of this invention is identical to the rstmentioned embodiment, the ball checks taking the positions shown in solid lines for refrigerant ilow in the direction of the solid arrows and those shown in dotted or phantom lines for refrigerant ow in the direction of the arrows in broken lines.

In the embodiment of FIG. 4, independent valve housings 68 and '70 are shown having inlets 72 and 74 connected to the conduits 34 and 40 respectively. Ball checks 76 and 78 within cages 80* and 82 are provided in the respective housings y68 and 79' and movable between a seated or closed position in the inlets and an open position at the inside end'o'f their cages. Each of the housings outlet at 84 and 86 to a common outlet conduit 88 and again, operation of these valves are indicated by solid and broken line ball positions like the embodiment of FIG. 3.

Thus, it will be seen that by this invention, a new unique refrigerant circuit is provided between the heat exchangers 10 and 12 including a pair of capillary tubing coils 26 and 28, each having the lproper ow restrictive characteristics for cooling and heating respectively. Further, by the use of a simple'two-way check valve, the refrigerant is caused to flow properly through the capillary coils in a highly effective manner, and moreover, it will be noted that flow of the refrigerant through the filter-dryer unit which is immediately in advance of the capillary tubing coils, is always in the same direction, thereby eliminating th'elproblem of backwash `and the introduction of trapped foreign particles into the refrigeration as a result thereof. VIn addition, the system is virtually self-operating, since no outside control is necessary for effective operation, the refrigerant flow itself providing the control.

Since the advantages of'this invention may be realized by many forms of the embodiment described, it is to be distinctly understood that the foregoing description is illustrative only rand not limiting, the true scope of the invention being defined by the appended claims.

We claim:

1. In a heat pump of the type including a closed circuit, reversible mechanical refrigeration system: an inside heat exchanger; an loutside heat exchanger; and a refrigerant circuitbetween said heat exchangers including means for reversing the refrigerant flow between said .heat exchangers; said refrigerant circuit comprising a .first length of capillary tubing, a second length of capillary tubing having diiferent iiowtpassage characteristics then said first length of tubings, a first bypass conduit in parallel with said first length of tubing, a second bypass conduit in parallel with said second length of tubing, a refrigerant conditioning means opening into and between said rst and second lengths of tubing, and valve means having inlets open to said rst and second bypass conduits and an outlet opening into said refrigerant conditioning means, said valve means being operable to permit refrigerant'ow through said first bypass conduit, rsaid conditioning means and said second length of tubing upon operation of the system in one direction and through said second bypass conduit, said conditioning means, and said first length of tubing upon reversal of the system.

2. In Ia heat pump of the type including a closed circuit, reversible mechanical refrigeration system: an inside heat exchanger; an outside heat exchanger; and a refrigerant circuit between said heat exchangers including means for reversing the refrigerant flow between said heat exchangers; said refrigerant circuit comprising a first-How restrictor, a second-how restrictor having diiferent flow passage characteristics than said first-how restrictor, a first bypass conduit in parallel with said first-flow restrictor; a second bypass conduit in parallel with said second-flow restrictor; refrigerant conditioning means opening into and between saidv first and second-how restrictors; and valve means having inlets open to said `first and second bypass conduits and an outlet opening into said refrigerant conditioning means, said valve means being operable to permit refrigerant iiow through said iirst bypass conduit, said conditioning means and said second-flow restrictor upon operation of the system in one direction and through said second bypass conduit, said conditioning means, and said rst-liow restrictor upon reversal of the system.

3. The apparatus recited in claim 2 in which said valve means comprises a two-way check valve having i alternately closable inlet passages.

ing an inside heat exchanger, and an outside heat exchanger; 'and a refrigerant circuit between said heat exchangers including means for reversing the refrigerant iiow between said heat exchangers; said refrigerant cir,V

cuit comprising a first length of capillary tubing, a second length of capillary tubing having ldierent iow passage characteristics than said first length of tubing; a first bypass conduit in parallel with said first length of tubing; a second bypass conduit in parallel with said second length of tubing; refrigerant conditioning means opening into and between said first and second lengths of tubing; and valve means having inlets open to said first and second-bypass conduits and an outlet opening into said refrigerant conditioningimeans, said valve means being operable to permit refrigerant liow through sa-id first bypass conduit, said conditioning means and said second length of tubing upon operation of the system in one direction and through said second bypass conduit, said conditioning means, and said first length of tubing upon reversal of the system.

References Cited in the tile of this patent UNITED STATES PATENTS 

